Mitochondrial RNA Polymerase Is Needed for Activation of the Origin of Light-Strand DNA Replication

作者：Fuste Javier Miralles; Wanrooij Sjoerd; Jemt Elisabeth; Granycome Caroline E; Cluett Tricia J; Shi Yonghong; Atanassova Neli; Holt Ian J; Gustafsson Claes M^*; Falkenberg Maria

来源：Molecular Cell, 2010, 37(1): 67-78.

DOI：10.1016/j.molcel.2009.12.021

Mitochondrial DNA is replicated by a unique enzymatic machinery, which is distinct from the replication apparatus used for copying the nuclear genome. We examine here the mechanisms of origin-specific initiation of lagging-strand DNA synthesis in human mitochondria. We demonstrate that the mitochondrial RNA polymerase (POLRMT) is the primase required for initiation of DNA synthesis from the light-strand origin of DNA replication (OriL). Using only purified POLRMT and DNA replication factors, we can faithfully reconstitute OriL-dependent initiation in vitro. Leading-strand DNA synthesis is initiated from the heavy-strand origin of DNA replication and passes OriL. The single-stranded OriL is exposed and adopts a stem-loop structure. At this stage, POLRMT initiates primer synthesis from a poly-dT stretch in the single-stranded loop region, After about 25 nt, POLRMT is replaced by DNA polymerase gamma, and DNA synthesis commences. Our findings demonstrate that POLRMT can function as an origin-specific primase in mammalian mitochondria.

• 出版日期2010-1-15